Studies on the role of the microtubular-microfilament system in the intracellular transport of beta granules will be continued. The perifusion system for in vitro studies of insulin secretion is used to study the pattern of insulin secretion and to determine the effect of anti-microtubular agents and of cytochalasin B on the first and second phase of glucose-induced insulin secretion. Studies on the pattern of secretion and the effect of the anti-mitotic agents on isolated islets and segments of pancreas of the rabbit and lizard are in progress. Studies will be continued on the use of alloxan as a probe to detect a glucoreceptor(s) in beta cells using the perifusion system. A method has been developed for the long-term culture of isolated islets and studies will be continued on the development of a technique for the establishment of a true monolayer culture of islet cells. Studies will be continued on the isolation of human islets and maintenance in vitro.